CVE-2021-29957: Mozilla Thunderbird

Medium severity, CVSS 4.3. EPSS: 0.9% chance of exploitation in the next 30 days.

If a MIME encoded email contains an OpenPGP inline signed or encrypted message part, but also contains an additional unprotected part, Thunderbird did not indicate that only parts of the message are protected. This vulnerability affects Thunderbird < 78.10.2.

Affected products

• Mozilla Thunderbird: before 78.10.2 (fixed in 78.10.2)

Published 2021-06-24. Last modified 2026-06-17.